CLINICAL CHARACTERISTICS OF VASODEPRESSOR, CARDIOINHIBITORY, AND MIXED CAROTID-SINUS SYNDROME IN THE ELDERLY

PURPOSE: Carotid sinus syndrome (CSS) is frequently overlooked as a ca use of syncope in the elderly. It is diagnosed when carotid sinus mass age (CSM) produces asystole exceeding 3 seconds (cardioinhibitory CSS) , a reduction in systolic blood pressure exceeding 50 mm Hg independen t of heart rate slowing (vasodepressor CSS), or a combination of the t wo (mixed CSS). Most published data pertain to the cardioinhibitory su btype. The recent availability of noninvasive phasic blood pressure mo nitoring has allowed accurate routine assessment of the vasodepressor response to CSM. The aim of this study was to assess the clinical char acteristics of vasodepressor, cardioinhibitory, and mixed CSS. PATIENT S AND METHODs. CSM was carried out on 132 consecutive patients over 65 years referred for investigation of dizziness, falls, or syncope. Mas sage was performed both supine and upright with continuous electrocard iographic and phasic blood pressure monitoring. Patients exhibiting gr eater than 1.5-second asystole were given 600 mug of intravenous atrop ine to abolish heart rate slowing and allow assessment of the pure vas odepressor response. RESULTs. Carotid sinus hypersensitivity was docum ented in 64 patients (mean age 81 +/- 7 years, 31 male). The response was vasodepressor in 37%, cardioinhibitory in 29%, and mixed in 34%. T hirty-six patients had recurrent syncope, 17 presented with unexplaine d falls, and the remainder had dizziness alone. Symptoms had been pres ent for a median of 24 months, and the median number of syncopal episo des was four. Twenty-five percent had sustained a fracture and, of the se, 93% had not experienced a prodrome. Head movement precipitated sym ptoms in 47% and vagal stimuli in 73%. Episodes were unwitnessed in tw o thirds of patients. Twelve patients who presented with falls denied syncope but had witnessed loss of consciousness during CSM. Mean cardi oinhibition was 5 +/- 2 seconds and mean vasodepression 61 +/- 9 mm Hg . The blood pressure nadir occurred rapidly at 18 +/- 3 seconds after massage, and baseline values were regained at 30 +/- 6 seconds. The cl inical characteristics of patients with vasodepressor, cardioinhibitor y, and mixed responses were similar. CONCLUSION: CSS is an underdiagno sed cause of dizziness, falls, and syncope in the elderly. The vasodep ressor form occurs more frequently than previously reported and has cl inical characteristics similar to those of the cardioinhibitory and mi xed subtypes. Elderly patients with this condition may deny syncope an d present with recurrent unexplained falls. CSM, ideally with noninvas ive phasic blood pressure monitoring, should be routinely performed in elderly patients with unexplained bradycardic or hypotensive symptoms .